If you are going to CF, I would keep the stock HS. Doesn't it exhaust out of the case?
http://www.newegg.com/Product/Produc...ercolor%207850
That one? If if it is getting 50% of the air out the case, how much are those AC coolers going to pump out of the case?
I only bring it up as Anandtech Prime mentions in their reviews how the benefits of the open air coolers are quickly negated in crossfire/sli setups.
They seem to be so popular because CF/SLI is a relatively rare implementation? Anyway, that is one factor I would consider.
I think you are running way too hot. I don't if the folding@home client really pushes a card, but I can run it all day and not climb above 52C with fan speed left on automatic. According to GPU Shark fan speed never exceeds 39%. My clocks are 1010/5000. My air flow is ok, but nothing to really brag about.
In the CCC, is your card activity pegging out the GPU? I wonder if it is "bouncing" around load wise, allowing for lower temps, etc. I have seen this with several DC apps. Also, what kind of PPD are you getting? Thank you